1. Field of Invention
This invention relates to a brake arrangement for a vehicle, more specifically the invention relates to a brake arrangement for a tractor having a cardan brake, or front axle brakes and separate left and right rear brakes.
2. Description of Related Art
The left and right rear wheels of modern tractors are provided with separate left and right brakes which are activated by the driver by respective foot pedals wheels to assist with steering. The tractor is further provided with a cardan brake which is activated together with both left and right brakes when both foot pedals are depressed together.
DE9204417 discloses a hydraulic brake arrangement in which two foot pedals are connected to two separate rear brakes and a front axle brake. The front axle brake is connected by a switch valve to both foot pedals which in turn operate two respective hydraulic cylinders. The switch valve activates when sufficient pressure is applied, that is when both cylinders are depressed. When only one cylinder is depressed there is not usually enough pressure to enable the front brake to be activated and as a result only one of the rear brakes is activated.
However, switch valves suffer from wear and tear and may start to open under lower pressures, that is, when only one foot pedal is depressed. This can lead to safety issues as a non reliable front brake may work in addition to a rear brake when it is not meant to. For example, the driver may only wish to apply one rear brake to steer around a corner, but if the front brake is also inadvertently applied there may be consequences if travelling at speed.